an atomic arrangement that has an unequal number of protons and electrons, hence as a whole bears a charge. (the charge is positive if there are more protons than electrons, and the charge is negative if there are more electrons than protons.

electron affinity

the pulling force that an atom has on another atom's electrons

polar

an arrangement where an equal number of opposite charges is distributed unequally, which results in one region of the arrangement being positively charged and a counterbalancing region being negatively charged. (commonly referred to as a separation of charge.)

chemical reaction

when the arrangement of atoms within molecules emerging from a collision is different than the arrangement entering the collision.

activation energy

the speed with which certain molecules must collide before they can undergo a chemical reaction.

reduction

an increase in the number of electrons in close association with an atom

monomer

the generic name given to small molecules that can be linked together to form large molecules (macromolecules).

polymer

the generic name given to any molecule formed by linking together many small molecules (linking together many monomers).

primary structure (of a protein)

a protein's specific sequence of linked amino acids

tertiary structure (of a protein)

the aspects of a protein's three-dimension shape determined by interactions among the variable groups in the same chain with each other and with the surrounding water medium.

enzyme

any protein that acts as a catalyst for a specific chemical reaction.

permease

any protein that aids in the movement of a specific type of molecule across a cell membrane.

DNA polymerase

the enzyme that, in association with an existing single-sided DNA molecule being used as a template to position different deoxyribonucleotides, catalyzes the linking of one deoxyribonucleotide to another (forming DNA)

RNA polymerase

the enzyme that, in association with DNA being used as a template to position different ribonucleotides, catalyzes the linking of one ribonucleotide to another (forming RNA)

gene

any segment of a DNA molecule that is transcribed

promoter

a segment of two-sided DNA molecule that due to its sequence has the right shape for RNA polymerase to bind to and then initiate transcription. Promoters designate the start of genes.

protein gene

any segment of DNA that codes for a functional protein (is a protein recipe)

mRNA

the generic name given to the RNA molecule that results from the transcription of a protein gene. (The mRNA formed is , in essence, the working copy of the protein recipe.)

genetic regulation

the turning on or off of transcription of any gene within a genome. (the "choosing" of which gene to transcribe)

regulatory protein

the generic name given to any protein that can bind to DNA (at a regulatory sequence) and influence (either positively or negatively) RNA polymerase's ability to bind to a gene's promoter (and subsequently initiate transcription).

tRNA

RNA molecules (made up of around 70 to 90 ribonulceotides) that play the role of translators during RNA translation. Each tRNA can be loaded with only one type of amino acid and has a unique anticodon.

point mutation

a change in a cell's DNA sequence due to the substitution of one deoxyribonucleotide with another deoxyribonucleotide having a different nitrogenous base. (a base substitution.)

deletion mutation

a change in a cell's DNA sequence due to the loss of one or more of the deoxyribonucleotides.

polyunsaturated fatty acid

group of molecules that consist of an acid (carboxyl) group attached to a long hydrocarbon chain with 2 or more double carbon bonds.

concentration gradient

a change in concentration across distance (in biology the term concentration gradient is used mostly to discuss a change in concentration across a membrane).

simple diffusion

net directional movement of some type of molecule across a membrane, where the movement is powered by the presence of a concentration gradient (movement from high to low), and the molecules cross simply because the membrane is permeable to this type of molecule.

facilitated diffusion

net directional movement of some type of molecule across a membrane, where the movement is powered by the presence of a concentration gradient (movement from high to low(, and the molecules cross the membrane with the aid of a channel protein or a permease.

active transport

net directional movement of some type of molecule across a membrane, where the movement goes against a concentration gradient so the movement is powered by some usable energy source supplied by the cell, and the molecules cross the membrane with the aid of a permease.

a step-wise series of chemical reactions (outputs of one become inputs to the next), where each reaction is facilitated by a different enzyme.

biosynthesis

the use of metabolic pathways to rearrange atoms in molecules available to the cell into biologically useful molecules.

nitrogen fixation

the process where molecular nitrogen (N2) is reduced to form ammonia (NH4)

autotroph

a cell able to reduce carbon dioxide (CO2) to a three-carbon sugar (called glyceraldehyde) (a cell able to perform the Calvin cycle.)

heterotroph

a cell unable to reduce carbon dioxide (CO2) to a three-carbon sugar, thus, must get their needed supply of simple sugars from autotrophic cells (via barter or theft).

essential nutrient

any nutrient that must be included in an organism's diet if normal function is to continue, typically because the molecule is both a needed component of metabolism and cannot be synthesized (from other available molecules) by the organism.

allosteric modulation

whenever a protein's function (whether it is turned on or off) is controlled by ligand-induced shape changes.

energy metabolism

how cells use an external usable energy source, such as light or a high energy molecule, to make the two needed cellular fuels -- ATP and NADPH

higher redox potential

a molecule (base-group) that in comparison to another molecule does not hold onto certain electrons (or hydrogen atoms) as tightly, so (during a chemical reaction) more readily donates electrons (to this other molecule) than accepts electrons (from this other molecules).

higher phosphorylation potential

a molecule (base-group) that in comparison to another molecule does not hold onto certain phosphates as tightly, so (during a chemical reaction) more readily donates a phosphate (to this other molecule) than accepts a phosphate (from this other molecule).

NADPH

the reduced form of NADP+ (NAD+ with an extra phosphate). It is used as the hydrogen donor whenever hydrogens are added on to other molecules during biosynthesis.

ATP

a molecule (an activated ribonucleotide) with bother a phosphate to transfer and relatively high phosphorylation potential. The directional movement of phosphates from ATP to other molecules is used to power many activities within a cell (e.g., turning on and off function of certain proteins, active transport, supplying the activation energy for energy-requiring biosynthetic reactions, generating motion).

NADH

the reduced form of NAD+. It is used as an initial donor in respiring cells. (in fact, it is the initial donor that can donate electrons into the first pump of the three-pump respiratory electron transport chain.)